The present invention relates generally to the field of mailing machines, and more particularly to a mailing machine which includes an apparatus for sensing thickness variations in the surface contour of pieces of mail to avoid printing postage indicia on mail pieces in areas on the mail pieces having surface contours unacceptable for printing.
Mailing machines have long been well known and have been developed over time to a high level of technical sophistication and complexity of features of operation. For these reasons, mailing machines have become very attractive to low, medium and high volume mailers, and technological advancements are constantly underway to further enhance the advantages and desirability of these machines. One of the advantageous features of operation is that modern day mailing machines can handle mail pieces having variable thickness, ranging from air mail thickness up to about a quarter of an inch, without having to make any mechanical adjustments to any the operating components of the mailing machine. This is a significant advantage of mailing machines from the economic standpoint in that relatively inexpensive, low volume mailing machines would not be provided with such adjustment mechanism in order to maintain a low cost, and the provision of such mechanism in a high speed, high volume mailing machine would inevitably have a deleterious effect on the speed of operation if the machine had to make mechanical adjustments to accommodate mail pieces of varying thickness.
One problem which arises in the operation of mailing machines is that of printing a postage indicia on a mail piece that does not have a smooth surface in the area in which it is desired to print a postage indicia. As is generally known, the principal function of a mailing machine is to print a postage indicia on a piece of mail in lieu of affixing a postage stamp. The mailing machine includes a base having a feed deck for supporting a mail piece, and in more sophisticated machines, a feeding mechanism for automatically and sequentially feeding successive mail pieces along the feed deck. The mailing machine also includes a postage meter including a printing device for printing the postage indicia on the mail piece, either while it is stationary or is being fed along the feed deck.
The U.S. Postal Service has promulgated regulations regarding the printing of postage indicia on mail pieces, the essence of which, so far as the present invention is concerned, is that the printed indicia must conform to a minimum standard of quality. Basically, the Postal Service regulations require that the postage indicia be printed in the upper right hand corner of an envelope if at all possible, that the imprint be readily legible, free from all forms of smudges or blurred print, and that there be no spurious markings adjacent to the indicia imprint.
The problem that arises is that it is virtually impossible to print a postage indicia on a mail piece which meets these requirements unless the surface of the mail piece on which the indicia is to be printed is relatively smooth and flat. This problem is characteristic of all forms of printing devices normally utilized in postage meters. The majority of postage meters utilize a metal or rubber die having the image of the postage indicia embossed thereon; the die is coated with ink and is pressed onto the surface of the mail piece to transfer the ink from the die to the mail piece. However, other printing processes can be utilized, such as dot matrix, thermal, ink jet and laser, but they all require a relatively flat and smooth surface on which to print the postage indicia.
The problem typically arises when mail pieces are improperly prepared for mailing. For example, if the mailer folds a large number of pieces of paper and inserts them into an envelope, the abrupt edge of the thick packet of folded paper forms a void within the envelope adjacent the edge, and if this edge is in the area when the postage indicia is to be printed, the printing die, or other printing element depending on the process used, will not be properly supported on the surface of the mail piece, which results in blank areas in the postage indicia imprint. Another problem frequently encountered is that of objects, such as staples or paper clips, being placed in envelopes which create bumps or other irregularities on the surface of the mail piece, resulting in a surface contour of sufficient irregularity that it is impossible to obtain an acceptable postage indicia imprint. As a practical matter, the only solution to these and other similar problems is simply to avoid printing on a mail piece in surface areas having this degree of surface irregularity.
Thus, there is a need for an apparatus that can be incorporated into a typical mailing machine that has the capability of scanning the surface contour of a mail piece in the area in which a postage indicia is to be printed to determine whether the surface contour is suitable for printing, and which actuates an instrumentality intended to prevent the printing from taking place in that area if the surface contour is determined to exceed a minimum acceptable level of surface contour irregularity.